March 2015 Approved for public release; distribution is unlimited. Roadmap to MaRIE Inside 3 Probing the unseen

4 Progress on the path optics required for high-energy x-ray light sources 5 Dattelbaum, Saxena named 2014 APS Fellows 6 Modeling quasi-brittle damage behavior in MaRIE’s next-generation XFEL metals builds on decades of Los Alamos R&D

LANSCE resumes Los Alamos National Laboratory’s proposed MaRIE facility is 120-Hz operations slated to introduce the world’s highest energy hard x-ray free electron laser (XFEL). 7 Neutron surface As the light source for the Matter-Radiation Interactions in Ex- scattering studies tremes experimental facility (MaRIE), the 42-keV XFEL, with demonstrate promise Key technologies bursts of x-ray pulses at gigahertz repetition for studying fast to address important dynamical processes, will help accelerate discovery and design aspects of actinide originally developed of the advanced materials needed to meet 21st-century na- surface chemistry at Los Alamos in the tional security and energy security challenges. 1980s and 1990s enabled the present XFEL Yet the science of free-electron lasers has a long and distin- 9 facilities currently in use guished history at Los Alamos National Laboratory (LANL), where for nearly four decades Los Alamos scientists have been Additively manufactured worldwide. U6Nb heat treated in situ performing research, design, development, and collaboration in SMARTS work in FEL science. The work at Los Alamos has evolved from low-gain amplifier and oscillator FEL development to high- brightness photoinjector development, and later, self-amplified In this early-1980s spontaneous emission (SASE) and high-gain amplifier photo (above left) Mi- FEL development. chael Whitehead works on FEL optics as part Advancing FEL physics of the AT-1 free electron Early FEL research at Los Alamos, beginning as far back as laser experiment. Above 1977, saw the achievement of experimental demonstrations right, a technician preps and theoretical understanding of the high-power FEL oscilla- equipment in the tors—in particular the FEL oscillation with side bands, the first 180 degree bend of the Energy Recovery demonstration of an FEL with energy recovery, the first high- Experiment. continued on next page

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 2 MaRIE’s next-generation ... cont. efficiency FEL with a tapered wiggler, and the first harmonic lasing in the ultraviolet realm.

The main driving force for this early work came from Strate- gic Defense Initiative Office funding to support a high-power FEL prototype design at Boeing with an ultimate goal of building a multi-megawatt FEL facility at White Sands Mis- sile Range in New Mexico.

Intensifying the science By 1985, with the invention of the radio frequency (RF) pho- toinjector at Los Alamos, LANL scientists began to charac- terize, understand, and design a new class of electron injec- tors that deliver electron beams with very high phase-space density—or high brightness.

Simulations of the first photoinjector experiments and early photoinjector designs at Los Alamos National Laboratory showed an unexpected increase in the beam brightness if a specific electron-focusing scheme was used. Los Richard Sheffield (right) and Dinh Nguyen at the Advanced Free Electron Laser Facility, around 1993. Alamos was the first to identify, explain, and use this ap- proach for the next generation of very high-brightness elec- Demonstrating success tron sources. In late 1990s, Los Alamos collaborated with the University of California, Los Angeles (UCLA) to demonstrate the principle These inventions led to the worldwide development of high- of SASE experiments in the infrared wavelength. The key brightness electron injectors that are being used as the front to SASE success was the high-brightness electron beams end of today’s XFEL. that were available from the Advanced FEL photoinjector at Los Alamos. The LANL team executed two high-gain SASE Recently, a continuous-wave normal-conducting RF photo- experiments: one with an undulator designed and built by injector has been tested at LANL that would have produced LANL; the other with a longer undulator designed and built the high-average-current electron beams to drive the U.S. Navy’s high-power FEL. continued on next page

Above: Jerry Watson (right) and Tom Wangler inspect an optical resonator mirror during the 1983 free electron laser dedication. Right: Scott Volz and Boyd Sher- wood construct the APEX photoinjector.

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 3 MaRIE’s next-generation ... cont. by a UCLA/LANL/Kurchatov Research Center collabora- tion and brought to Los Alamos for experiments. The LANL/ UCLA team was the first to show large SASE gains in free space. These experiments demonstrated the necessity of using the high-brightness electron beams from the RF pho- toinjectors for the high-gain FEL amplifiers.

Following the initial success of the pioneering infrared SASE experiments at LANL, other laboratories successfully demonstrated SASE lasing in the visible, ultraviolet, and, finally, x-ray wavelengths. A multi-laboratory collaboration A researcher adjusts instruments as part of free-electron that included LANL was formed to design and build an x-ray laser development studies conducted at Los Alamos in the SASE FEL called the Linac Coherent Light Source (LCLS) early 1980s. at SLAC. In 2008, SLAC successfully demonstrated SASE lasing with the LCLS at angstrom wavelength, claiming the Probing the unseen title of the world’s first hard XFEL. Free-electron lasers defined Los Alamos National Laboratory has continued to actively Free-electron lasers (FELs) are powerful sources of tunable engage in developing state-of-the-art RF photoinjectors, su- coherent radiation. An FEL light pulse can put out milli- perconducting accelerators, advanced beam manipulation, joules of energy in less than 100 femtoseconds (10 trillion and x-ray self-seeding techniques geared toward the next- in a second). The wavelength of the light is adjustable from generation XFEL. millimeters to fractions of nanometers by changing the elec- tron energy and the magnetic system. Peak power arises when a multi-gigawatt electron beam traverses a series of MaRIE will build upon this rich history in FELs by enabling alternating magnets known as a wiggler, interacts with the LANL’s strategic planning goal that includes next-generation radiation, and in the process bunches electrons spaced one facilities. Los Alamos researchers are designing a 42-keV wavelength apart. The bunched electron beam emits radia- XFEL that specifically addresses the application of coher- tion coherently, that is, the emitted radiation waves are in ent x-rays to LANL’s national security missions. This MaRIE step with one another. The FEL is tunable by adjusting how XFEL will facilitate delivery of nuclear and global security fast the electron beam travels by increasing or decreasing solutions, enable innovative science and engineering excel- its kinetic energy, or by adjusting the period or the magnetic lence, and attract and retain a vital future workforce. field of the wiggler.

Los Alamos National Laboratory is proud to be the host of MaRIE’s x-ray free-electron laser the International FEL Conference, scheduled for 2017 in Multiple radiographs and coherent x-ray diffraction patterns Santa Fe, New Mexico. collected at time steps through the evolution of dynamic processes can deliver critical information on the dynamic Technical contacts: Dinh Nguyen, Bruce Carlsten, response to various impulsive loading conditions, such and Richard Sheffield as shock waves or radiation interactions. Los Alamos has pioneered the science and technology of flash radiography A brazed copper LINAC structure for the advanced FEL since the earliest days of the Laboratory. For example, in LINAC, designed and fabricated by the Laboratory’s AT-1 the late 1990s Los Alamos scientists invented the technique group of Accelerator Technology Division, dedicated of charged particle radiography, using the 800-MeV proton August 1991. beam at the Los Alamos Neutron Science Center to gener- ate multiple “stop-action” radiographs of dynamic systems during a single event.

MaRIE will have the capability to provide a series of im- ages, a movie, over time scales of microseconds through thick samples of material undergoing a dynamic event. Cur- rent brilliant x-ray FEL sources focus their beams on small (1-micron or so) size spots with few atoms, and the inelastic scattering deposits enough energy to turn the sample into a plasma.Illumination with higher energy x-rays and a larger spot size and sample volume can reduce the intensity of deposited energy from the x-ray probe, albeit while ac- cepting spatial resolution that is larger. This is exactly the mesoscale on which MaRIE is focused.

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 4

Left: Peter Kenesei (Advanced Photon Source, APS), Ali Mashayekhi (APS), Amanda Wu (Lawrence Livermore National Laboratory), Kenneth Evans-Lutterodt (Brookhaven National Laboratory) staging additively manufactured U6Nb measurements using kinoform lens at the APS 1-ID beamline.

Science and technology on the roadmap to MaRIE Progress on the path optics required for high-energy x-ray light sources

In a promising step toward the development of the wide range of optics needed by MaRIE (Matter Radiation Interac- tions in Extremes) and other high-energy x-ray light sources, Los Alamos researchers, in collaboration with Brookhaven National Laboratory (BNL) and the Advanced Photon Source (APS) at Argonne National Laboratory, successfully explored the possibility that new diffractive optics can efficiently focus Above: Main high-energy photons (E > 50 keV). collaborator Sarjivt Shastri MaRIE, the Laboratory’s proposed facility for time-dependent (APS). materials science at the mesoscale, will ultimately provide a bright source of high energy x-ray photons; but without At left, Richard Sheffield checks focusing elements, the size of the beam on the sample will distances for not allow the full potential of the source to be exploited. The lens focal length researchers fabricated two types of refractive optics—the and efficiency familiar solid refractive lens in an unconventional material measurements (diamond), and the less familiar kinoform shape in silicon. at APS 1-ID Their work, in preparation for MaRIE, demonstrated the use beamline. of silicon kinoform lenses and diamond solid refractive lens- es to successfully focus beams of high-energy x-ray photons with energies between 50-100 keV, producing focal spots as small as 230 nm.

Many materials relevant to national security are high-density materials, and these materials are relatively opaque to low energy (E < 30 keV) x-ray photons. To study and understand these materials, researchers would like to deeply probe these materials with sub-millimeter x-ray beams, enabling micron-scale characterization. This characterization in com- bination with modeling, will give better insight into materials behavior in the extreme environments of interest. Higher en- ergy photons interact less strongly with matter, can penetrate more deeply into material, and deposit less energy—result-

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Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 5 Progress on ... cont. ing in less probe heating. This weaker interaction with mat- Dattelbaum, Saxena named 2014 APS Fellows ter is exactly what makes conventional focusing optics such as mirrors or zone plates either ineffective, inefficient, The American Physical Society (APS) recently elected Dana or expensive. Dattelbaum (Shock and Detonation Physics, WX-9) and Avadh Saxena (Physics of Condensed Matter and Complex The top panel in the figure on the previous page is a visible Systems, T-4) 2014 Fellows. light image of a silicon wafer of size approximately 1 by 3 cm on which are etched 10 kinoform lenses. The Dattelbaum was cited for “pioneering studies of dynamic design and fabrication with electron beam lithography and properties and excited state behavior of materials using reactive ion etching was performed at the Center for Func- advanced diagnostics techniques and for her leadership and tional Nanomaterials at BNL and at the Cornell Center for service to the Society and the Shock Physics community.” Functional Nanomaterials at Cornell University. The lenses She was nominated by the Topical Group on Shock Com- were tested at the Advanced Photon Source at Argonne pression of Condensed Matter. National Laboratory. Shown in the middle panel is an x-ray transmission image of the lens showing some of the micro- Dattelbaum’s experiments in shock sensitivity and dynam- structure of the lens. The bottom image shows a knife-edge ics of explosives support simulations of nuclear weapons scan depicting a spot size of 230 ± 20 nm at 51.2 keV. performance and enhance the safety of the nation’s nuclear stockpile. Dattelbaum currently probes explosives during The gain was 87 ± 4, i.e. the resultant flux density on the dynamic events but is often restricted to examining surface sample is equivalent to increasing the light source ring cur- phenomena. Her current research is on the roadmap to rent by a factor of 87. A 1 m and a 2 m lens were also test- MaRIE (Matter Radiation Interactions In Extremes), where ed. The 2 m lens had a gain of 181 and a spot size of 1.0 ± she will be able to investigate what is happening in the bulk 0.1 microns. Finally, the researchers made a first attempt at material. Dattelbaum received a PhD in organic chemistry using a solid refractive diamond lens to focus hard x-rays, from the University of North Carolina at Chapel Hill and and focusing functionality was observed, but given that joined the Laboratory as a Director’s Postdoctoral Fellow. diamond fabrication technology is not as advanced as sili- con fabrication technologies, more research is need to im- Saxena was nominated for “foundational contributions prove performance. to phase transitions in functional materials and nonlinear excitations in low-dimensional electronic materials.” He was Participants include Richard Sheffield (Experimental Physi- nominated by the Division of Materials Physics. cal Sciences, ADEPS), Kenneth Evans-Lutterodt (Brookhav- en National Laboratory), Sarjivt Shastri (Advanced Photon Phase transitions can be highly transient processes, and Source), Don Brown (LANL), A. Stein, (Cornell University), Saxena’s work has provided a theoretical foundation for M. Metzler (Cornell University) and P. Kenesei (Argonne Na- understanding these events. With the exquisite temporal tional Laboratory). and spatial resolution of MaRIE, Saxena’s predictions can be tested experimentally. Saxena received a PhD in physics The research, which was funded by the MaRIE program from Temple University and was a visiting scientist at Los (Cris Barnes, capture manager), supports the Laboratory’s Alamos before joining the Lab as a technical staff member. nuclear deterrence mission and Materials for the Future sci- ence pillar. APS nominations are evaluated by the Fellowship Commit- tee of the appropriate APS division, topical group or forum, Reference: “Kinoform Lens Focusing of High-Energy X- Rays (50-100 keV),” Proc. SPIE, 9207, 920704-1-9 (2014). continued on next page

Technical contact: Richard Sheffield

Dana Dattelbaum Avadh Saxena

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 6 APS Fellows ... cont. or by the APS General Fellowship committee. After review by the full APS Fellowship Committee, the successful can- didates are elected by the APS Council. APS is a non-profit membership organization working to advance and diffuse the knowledge of physics through its outstanding research a) journals, scientific meetings, and education, outreach, advo- cacy and international activities. APS represents more than 50,000 members, including physicists in academia, national laboratories and industry in the United States and through- out the world. b) Modeling quasi-brittle damage behavior in metals c) Los Alamos National Laboratory (LANL) scientists have developed a new material strength and damage model that accounts for brittle-ductile transitions in the mechanical response of quasi-brittle metals. Fracture behavior is ac- counted for by evolving tensile and compressive damage Damage evolution of a section of a thin walled beryllium separately using energy-based criteria and tensor represen-  cylinder with a constant internal pressure applied at times: a) tation theory. Uniquely, this continuum-scale material model 10.0 μs, b) 18.5 μs, c) 25.5 μs. The red regions show tensile can account for mesoscale deformation and damage mech- damage, specifically crack formation. Green regions show anisms. For example, strength and plasticity are built on a shear band formation. mechanism-based, viscoplastic framework that can account accounts for the effects of brittle-ductile transitions in mate- for mechanisms such as deformation twinning. rial response. Researchers on this project include Abigail Hunter (Computational Physics, XCP-1), Alek Zubelewicz This novel model has also been recently implemented into (retired from Physics and Chemistry of Materials, T-1), and Lagrangian Applications Project (LAP) codes. This frame- Esteban Rougier (Geophysics, EES-17). work allows for the study of brittle failure and brittle-ductile transitions in the material response, something that has Technical Contact: Abigail Hunter not been previously possible in macro-scale continuum codes at LANL. Because tensile and compressive damage evolve separately, visualization of mesoscale deformation LANSCE resumes 120-Hz operations mechanisms such as crack formation and shear banding is possible. Due to the viscoplastic framework, strength and The Los Alamos Neutron Science Center (LANSCE) plasticity responses in this model produce smooth transi- resumed 120-Hz operations in early December, providing tions between the elastic and plastic regimes of stress-strain the neutron flux to meet a Level 2 NNSA milestone and curves. Early comparisons of simulation results to flyer-plate enabling faster completion of a variety of nuclear physics experimental data are favorable. experiments running at the accelerator-based user facility. LANSCE provides the scientific community with intense This work is an example of Science on the Roadmap to Ma- sources of neutrons for experiments supporting civilian and RIE, LANL’s proposed experimental facility for Matter-Radi- national security research. ation Interactions in Extremes. This model is an example of a computational tool that can be informed and validated by The resumption is the result of LINAC Risk Mitigation ac- the experimental results produced by MaRIE. Such a con- tivities. Improvements include a new, fully designed radio nection between modeling and experimental efforts would frequency (RF) power amplifier, new water systems for enhance LANL’s understanding of material behavior under the drift tube linac, and upgrades to the linear accelerator extreme conditions, and also provide a distinctive capability control systems. Scientists, engineers, and technicians from to predict overall material response. Accelerator Operations and Technology (AOT) Division de- signed, tested, and installed the sophisticated systems. The This work is funded by the Advanced Simulation and Com- result enabled a return to high-power operations that had puting (ASC) Program through the Integrated Codes (IC) ceased in 2006 due to aging high-power radio frequency and Physics and Engineering Models (PEM) program ele- equipment. ments. This work supports LANL’s Nuclear Deterrence and Stockpile Stewardship mission area and the Materials for the Future science pillar by providing a predictive tool that continued on next page

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 7 LANSCE... cont.

Fission Time Projection Chamber Chi-Nu Detector Array

The new Diacrode amplifier-based RF systems for the DTL, part of the LINAC Risk Mitigation activities The high-power neutron flux from the higher proton pulse that enabled a repetition rate enables improvements in data collection by a return to 120-Hz factor of 2.5 for the fission Time Projection Chamber and the operations at Chi-Nu array. Both are NNSA Weapons program Science LANSCE. Campaigns-funded instruments and active collaborations between Los Alamos and Lawrence Livermore national laboratories. The fission Time Projection Chamber is de- signed to allow more precise fission cross-section measure- Technical contacts: Kurt Schoenberg and John Erickson ments than were possible with previously used techniques. This benefits both NNSA Defense programs and DOE Neutron surface scattering studies Nuclear Energy programs through increased understanding demonstrate promise to address important of energy generation and accuracy in modeling of reactors and weapons. Chi-Nu measures the energy spectrum and aspects of actinide surface chemistry number of neutrons emitted in fission, improving confidence in the outgoing fission neutron spectrum as a function of Actinides and actinide oxides exhibit some of the most in- incident neutron energy. triguing and challenging chemistry known. Frequently their compositions are not stoichiometrically precise, and their The 120-Hz operation also enables the development of new oxide structures can change dramatically under various research facilities utilizing the LANSCE LINAC. The im- environmental conditions. Studies of actinide surfaces and provements are an example of the Laboratory’s LINAC ac- surface initiated chemical evolution of bulk materials, at the celerator expertise that could be used to design, build, and core of the LANL mission, are even more challenging. The operate the MaRIE XFEL, the world’s highest energy hard scientific challenge is to identify, measure, and understand (42-keV) x-ray free-electron laser, which is at the core of the the aspects of their surface chemistry—which can depend Lab’s proposed Matter-Radiation Interactions in Extremes on preparation methodology and aging conditions—without disturbing their microstructures. For example, the details of experimental facility for control of time-dependent material 239 performance. chemical evolution on Pu surfaces, particularly the Pu va- lence state, are important for understanding stockpile aging, John Lyles and staff (RF Engineering, AOT-RFE) led the given the reversible auto-reduction of PuO2 to Pu2O3 under high power RF systems effort; Mechanical Design Engineer- various environments. The other key science question in- ing (AOT-MDE), Instrumentation and Controls (AOT-IC), volves reactivity of different actinides with gases and liquids and Mechanical and Thermal Engineering (AET-1) staff at the atomic and nanoscales. performed water systems and instrumentation and control work. The NNSA Readiness in Technical Base and Facilities Recent data generated using the ASTERIX and SPEAR (RTBF) program funded the LINAC Risk Mitigation work. neutron spectrometers at the Los Alamos Neutron Science LANSCE activities support the Lab’s Nuclear Deterrence Center (LANSCE) represents the first measurement of and Energy Security mission areas and the Nuclear and PuOx, UOx and Th films using neutron reflectometry (NR). Particle Physics, Science of Signatures, and Materials for The results hold promise that neutron surface scattering the Future science pillars. continued on next page Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 8 Neutron surface... cont. techniques (with reflectometry, grazing incidence diffrac- tion, and grazing incidence small angle scattering) will give unique insight into these important systems from sub-nm to μm length scales. Such studies of actinides surface chem- istry and reactivity are relevant to a broad spectrum of prob- lems: from environmental remediation to stockpile stewardship.

Neutrons provide a distinct advantage over x-rays in struc- tural characterization of lighter elements and accessibility of buried interfaces, making them an excellent probe for studying and mapping different hydride and oxide forms at surfaces and interfaces of heavy metals. Neutrons, due to their excellent penetrability and comparable scattering cross sections for actinides and isotopes of interest (O2, H2, D2, etc.), are ideally suited to study Å length scales changes in the chemistry of these materials.

239 Preliminary studies of neutron reflectometry of PuOx,

UOx and Th thin films were performed at LANSCE using ASTERIX and SPEAR. Several nanometer-thick films of

PuOx were grown on a zirconia substrate with approximately 2 1 cm surface area (total mass of PuOx less than 50 micro- grams) by polymer assisted deposition. The films of UOx and Th were prepared by DC-magnetron sputtering. These films Figure 1: Top- PuO NR data (symbols with error bars) and fits were investigated by neutron reflectometry and off-specular x (lines) corresponding to scattering length density models pre- neutron scattering to determine their thickness and composi- sented at the bottom. Green and blue–pure zirconia interfaces tion. In case of the PuOx film (Figure 1), the preliminary neu- with different roughness values. Inclusion of the PuO2 layer tron scattering data analysis quantifies the characteristics of (red) was essential to fit the data. a high quality film. The scattering length density (SLD) dis- tribution normal to the surface is homogenous and matches used as nuclear fuel, could provide an ideal combination of 239 features between metal fuel and oxide fuels. These include almost exactly the literature value for crystalline PuO2. No the thermo-physical properties relative to metal fuel and lower density region between PuO2 and zirconia substrate or other chemically different layer at the air interface were chemical stabilities similar to oxide fuel. ThO fuel shows many advantages with enhanced performance over the observed. The air/PuO2 and zirconia/PuO2 roughness were ~20 and ~5 Å r.m.s, respectively. Very small off-specular traditional oxide fuels: namely, high-fissile density (good scattering testifies to a high degree of in-plane order within breeding performance), high-thermal conductivity, and high- the film. melting point with adequate chemical stability.

In the case of Th films in situ time dependent neutron re- Using NR, researchers were able to demonstrate the capa- flectivity was used to measure changes in the SLD and bility to determine the chemical speciation signatures on a thickness of the material during a controlled oxidation pro- complex uranium oxide family. Namely, both the surface and cess (Figure 2). As the oxidation progressed, several sub- underlying layers of the uranium oxides were characterized stoichiometric thorium oxides, ThOx (x<1), preferentially with Å-level-resolution. This capacity cannot be achieved formed between the thorium metal and its dioxide layer were using x-ray scattering since it is not capable of distinguish- observed. The SLD value of these new oxides increased un- ing between U3O8 and α-U3O8 especially at the nanometer til a constant value for ThO was reached. These NR experi- scale. Moreover, the Å-resolution measurement of the ments demonstrated that the kinetically favored ThO can be chemical speciation and its spatial distribution for nuclear preferentially generated over the thermodynamically favored materials of technological importance could foster a revolu- tion in understanding their oxidative behavior by providing ThO2. The near perfect stoichiometric lattice and relative low new capabilities to exploit rich forensic information and ex- O solubility in the ThO2 top layer limits the availability as well as diffusivity of O species interacting with ThO, and hence tend fundamental knowledge to assess or interpret the sig- prevents or slows the successive further oxidation. The natures, while leaving the opportunity to employ additional, conclusion of this work is that solid-state thorium monoxide, possibly destructive methods of analysis. The development measured for the first time, is produced at material inter- faces. The practical implication of this material, for example continued on next page

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 9 Neutron surface ... cont. of this method may also be applicable to a broad range of other scientific disciplines. The work is an example of science on the roadmap to Ma- RIE, the Laboratory’s proposed experimental facility for con- trol of time-dependent material performance. Using MaRIE’s advanced capabilities, the combination of x-ray and neutron surface scattering methods will provide unprecedented, time-resolved access to structural properties of actinides and their surfaces from atomic- to meso- scales. A complete picture of the chemical depth profiles and surface topog- raphy of hydrides and oxides formed at metal interfaces can be provided. The highly penetrative nature of neutrons together with high energy x-rays will facilitate these studies over a wide range of chemical environments, pressures, and temperatures.

Figure 2: (a) NR spectra in the form of R vs. Qz obtained on Researchers include Daniel Schwartz, David Moore, and thorium coated mono-crystalline α-quartz at mid-stage (Run Joe Martz (Nuclear Materials Science, MST-16); Brian Scott, #6) and near-final-stage (after Run 7) of controlled oxidation

Eve Bauer and Erik Watkins (Materials Synthesis and In- after a given exposure to ~100 ppm O2 in Ar; Run 6: 150°C af- tegrated Devices, MPA-11); Ann Junghans (Polymers and ter ~300 min; Run 7: 150°C after ~250 min; Run 14: 150°C after Coatings, MST-7), Peng Wang (formerly Lujan Center, LC- ~700 min. The data is represented by open circles. The solid LANSCE), Kirk Rector and Heming He (Physical Chemistry lines through the data points are the best-fits based on the real space SLD models presented in (b). The zero thickness is and Applied Spectroscopy, C-PCS), David Allred (BYU, set at the quartz substrate/Th film interface. Provo), and Jarek Majewski (Center for Integrated Nano- technologies, MPA-CINT).

This research was supported by the Primary Assessment Technologies Campaign, the Los Alamos Laboratory Direct- ed Research and Development program and a G. T. Sea- borg Institute postdoctoral fellowship (to H. He). This work benefited from the use of the time-of-flight neutron reflec- tometer SPEAR and ASTERIX at Lujan Neutron Scattering Center at LANSCE until 2014 funded by the DOE Office of Basic Energy Sciences and Los Alamos National Laboratory Figure 3: (a) NR spectrum in the form of R vs. Qz from UOx under DOE Contract DE-AC52-06NA25396. coated mono-crystalline α-quartz. The data is represented by open circle with error bars indicating one standard deviation. Technical contact: Jarek Majewski The solid lines through the data points are the best-fit corre- sponding to the SLD profiles shown in (b). Additively manufactured U6Nb heat treated in situ in SMARTS Results aid materials processing techniques

In an attempt to understand materials processing being done at Lawrence Livermore National Laboratory (LLNL), additively manufactured U6Nb was recently heat treated in situ in the Spectrometer for Materials Research at Temperature and Stress (SMARTS), at the Los Alamos Neutron Science Center. The results provided valuable data for improving LLNL’s additive manufacturing techniques, and is companion work done on similar material at the Advanced Photon Source as illustrated in the photo at the top of page 4.

Additive manufacturing (AM) represents a relatively new fabrication paradigm in which parts are built from the ground up to final geometry, as opposed to traditional manufacture, where large blanks are produced and machined to final dimensions. AM needs to be scientifically examined because the process is very different from traditional manufacture.

Traditionally processed U6Nb usually has a monoclinic (a’’) crystal structure. Previous experiments at SMARTS showed that as-processed, the U6Nb material additively manufactured at Livermore has a two-phase structure comprised of roughly equal g amounts of the monoclinic and tetragonal ( 0) crystal structure. Following the Livermore heat-treatment (10 hours at 1000°C), g the material is single phase 0. continued on next page

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE 10 Additively ... cont. An as-processed sample was heated in-situ on SMARTS with a heating rate of 100°C/min followed by a 1000°C (in the cubic (g) phase) hold for 10 hours. The timing of the heat treatment matches well with the data integration time (~5 minutes) on SMARTS. The figure shows several diffraction patterns, before and after heat treating, when first reaching 1000°C and after 10 hours at 1000°C.

The diffraction data when the sample first reached 1000°C is indistinguishable from that 10 hours later. Moreover, the final diffraction pattern after the heat treatment was consis- tent with the sample heat treated ex situ at Livermore. The conclusion is inescapable: the parts of the microstructure that can be monitored with diffraction, i.e. the Nb concentra- tion, internal stress, dislocation density, and texture, did not change during the hold at 1000°C, and therefore, must have changed during the heating phase.

These results can be used by Livermore to better design the heat treatment process to achieve the final microstructural goal. Moreover, the work represents the philosophy driving MaRIE, i.e. understanding manufacturing process towards optimization, control, certification, and qualification. The limited data rate at SMARTS allows researchers to monitor the microstructure during the relatively long heat treatment. Shown are several diffraction patterns, before and after heat In contrast, the very high data rate associated with MaRIE treating, when first reaching 1000°C and after 10 hours at would allow monitoring of the material deposition process 1000°C, demonstrating that the parts of the microstructure itself, which happens in a fraction of a second. MaRIE (Mat- that can be monitored with diffraction must have changed during the heating phase. ter-Radiation Interactions in Extremes) is the Laboratory’s proposed experimental facility for control of time-dependent material performance.

The work, which was funded by the Primary Assessment Technologies Campaign, supports the Laboratory’s Nuclear Deterrence mission and Materials for the Future science pillar. Researchers include Amanda Wu (LLNL) in collabora- tion with Don Brown and Bjorn Clausen (Materials Science in Radiation & Dynamics Extremes, MST-8).

Technical contact: Don Brown

To learn more about MaRIE, please see marie.lanl.gov, or contact Cris Barnes, capture manager, at [email protected].

Roadmap to MaRIE, featuring science and technology highlights related to Los Alamos National Laboratory’s proposed experimental facility, is published by the Experimental Physical Sciences Directorate. For information about the publication, please contact [email protected].

Los Alamos National Laboratory, an affirmative action/equal opportunity employer, is operated by Los Alamos National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396. By acceptance of this article, the publisher recognizes that the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. Government purposes. Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the U.S. Department of Energy. Los Alamos National Laboratory strongly supports academic freedom and a researcher’s right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness.

Los Alamos National Laboratory | Science and technology news and highlights on the roadmap to MaRIE LA-UR-15-22270 Approved for public release; distribution is unlimited.

Title: Roadmap to MaRIE March 2015

Author(s): Barnes, Cris William

Intended for: Newsletter Web

Issued: 2015-03-30 Disclaimer: Los Alamos National Laboratory, an affirmative action/equal opportunity employer,is operated by the Los Alamos National Security, LLC for the National NuclearSecurity Administration of the U.S. Department of Energy under contract DE-AC52-06NA25396. By approving this article, the publisher recognizes that the U.S. Government retains nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or to allow others to do so, for U.S. Government purposes. Los Alamos National Laboratory requests that the publisher identify this article as work performed under the auspices of the U.S. Departmentof Energy. Los Alamos National Laboratory strongly supports academic freedom and a researcher's right to publish; as an institution, however, the Laboratory does not endorse the viewpoint of a publication or guarantee its technical correctness.